Computers and Health






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Computers and Health

Computers and Health





Created by

Andrey Tarassov

Tallinn 1999


ithin the past two years, substantial media attention has been directed at

potential adverse health effects of long-term computer use. Renewed

concerns about radiation, combined with reports of newly-recognized

"repetitive stress injuries" such as carpal tunnel syndrome, have led some

to call for regulation in the workplace and others to rearrange their

offices and computer labs. There is little evidence that computer use is on

the decline, however. On the contrary, more people are spending more time

doing more tasks with computers -- and faculty, students and staff at

colleges and universities have some of the most computer-intensive work

styles in the world.

If, as is widely suspected, health effects are cumulative, then many of us

are at risk in our offices, labs, dormitories, and homes. Unfortunately,

many years will be required before epidemiological studies can provide

definitive guidelines for computer users, managers, furniture suppliers,

and office designers. In the interim, individuals and institutions must

educate themselves about these issues and protective measures.

One set of issues concerns workstation design, setup, and illumination,

together with users' work habits. The City of San Francisco, which recently

enacted worker safety legislation, cited research by the National Institute

of Occupational Safety and Health (NIOSH) into VDT operator complaints of

eyestrain, headaches, general malaise, and other visual and musculoskeletal

problems as the rationale for imposing workplace standards, to be phased in

over the next four years.

A second set of issues relates to suspected radiation hazards, including

miscarriage and cancer. A special concern with radiation is that nearby

colleagues could be affected as well, since radiation is emitted from the

backs and sides of some terminals. The most recent NIOSH study is

reassuring, but some caution still seems prudent.

Ergonomics and work habits

Most people can ride any bicycle on flat ground for a short distance with

no problems. On a fifty mile ride over hilly terrain, however, minor

adjustments in seat height, handlebar angle, and the like can mean the

difference between top performance and severe pain. Similarly, occasional

computer users may notice no ill effects from poorly designed or badly

adjusted workstations, whereas those who spend several hours a day for many

years should pay careful attention to ergonomics, the study

of man-machine interfaces.

The key to most workstation comfort guidelines is adjustability--to

accommodate different body dimensions, personal workstyle preferences, and

the need to change positions to avoid fatigue. A recommended working

posture shows the body directly facing the keyboard and terminal, back

straight, feet flat on the floor, eyes aligned at or slightly below the top

of the screen, and thighs, forearms, wrists, and hands roughly parallel to

the floor. Achieving this posture may require:

. A chair with a seat pan that adjusts both vertically and fore-and-aft, an

adjustable height backrest, and adjustable tilting tension

. An adjustable height work surface or separate keyboard/mouse tray (note

that many keyboard trays are too narrow to accommodate a mouse pad,

leaving the mouse at an awkward height or reach on the desktop)

. A height adjustment for the video display (a good use for those manuals

you'll never read!)

. An adjustable document holder to minimize head movement and eyestrain

. Adjustable foot rests, arms rests, and/or wrist rests.

Studies show that many people are unaware of the range of adjustments

possible in their chairs and workstations. Although the best chairs permit

adjustment while seated, you may have to turn the chair upside down to read

the instructions. (Be careful not to strain your back while upending and

righting the chair!) If your posture deviates substantially from that in

the diagram--or if you are experiencing discomfort--experiment with

adjustments or try exchanging chairs or workstations

with colleagues. A posture cushion, which maintains the natural curvature

of the spine and pelvis while supporting the lumbar region, may also prove

helpful. It should be noted that any adjustment may feel uncomfortable for

a week or so while your body readjusts itself.

(Some people have been advised by their physicians to use a backless

"Balans" chair, which minimizes compression of the spine and shifts the

body weight forward with the aid of a shin rest. This posture may be

uncomfortable, however, since it requires stronger abdominal and leg

muscles than conventional sitting positions. The Balans chair is not

recommended for overweight or exceptionally tall persons)

Light and glare

Eyestrain, headaches, and impaired vision are often a product of improper

illumination resulting in glare, which is light within the field of vision

that is brighter than other objects to which the eyes are adapted. Both

direct glare from sunlight and lighting fixtures directed at the user's

eyes and indirect glare due to reflections from

video screens or glossy surfaces are common problems for VDT users.

Many offices are too bright for computer use, which may be a carryover from

the days when paperwork required such brightness or the result of many

office workers' preferences for sunlight and open windows. A NIOSH study

recommends 200-500 lux for general office work; other sources suggest 500-

700 lux for light characters on dark monitors and somewhat more for dark-on-

light. If documents are not sufficiently illuminated, desk lights are

recommended in preference to ceiling lights, which

increase reflections from video screens. Reducing overhead lighting could

also result in substantial energy savings.

VDT workstation placement is also important. Terminal screens should be

positioned at right angles to windows, so sunlight is neither directly

behind the monitor nor behind the operator, where it will reflect off the

screen. If this is infeasible, blinds or drapes should be installed.

Screens should also be positioned between rows of overhead fixtures, which

can be fitted with baffles or parabolic louvers to project light downward

rather than horizontally into the eyes or terminal screens.

Some users have found filters placed in front of the screen to be effective

in reducing reflections, however some dimming or blurring of the display

may result. Experts 1advise trial and error, since the best solution

appears to depend upon specific conditions and user preferences. Finally,

if you wear glasses or contact lenses, be sure your physician is aware of

the amount of terminal work you do; special lenses are sometimes necessary.

Bifocals, in particular, are not recommended for extensive terminal work,

since the unnatural neck position compresses the cervical vertebrae..

Breaks and exercises

Working in the same position for too long causes tension buildup and is

thought to increase the risk of repetitive motion injuries, such as carpal

tunnel syndrome. Remedies include changing postures frequently, performing

other work interspersed with computing (some studies recommend a 10-15

minute break from the keyboard every hour), and doing exercises such as

tightening and releasing fists and rotating arms and hands to increase

circulation. Be aware, also, that the extra stress created by deadline

pressure exacerbates the effects of long hours at the computer.

Radiation hazards

For at least a decade, concerns have been raised about possible effects of

radiation from video display terminals, including cancer and miscarriages.

Earlier fears about ionizing radiation, such as X rays,

have been laid to rest, since these rays are blocked by modern glass

screens. Also well below exposure standards are ultraviolet, infrared, and

ultrasound radiation.

More recent controversy surrounds very low frequency (VLF) and extremely

low frequency (ELF) electromagnetic radiation produced by video displays'

horizontal and vertical deflection circuits, respectively. Researchers have

reported a number of ways that electromagnetic fields can affect biological

functions, including changes in hormone levels, alterations in binding of

ions to cell membranes, and modification of

biochemical processes inside the cell. It is not clear, however, whether

these biological effects translate into health effects.

Several epidemiological studies have found a correlation between VDT use

and adverse pregnancy outcomes, whereas other studies found no effect. The

most recent analysis, published this year by NIOSH, found no increased risk

of spontaneous abortions associated with VDT use and exposure to

electromagnetic fields in a survey of 2,430 telephone operators. This

study, which measured actual electromagnetic field strength rather than

relying on retrospective estimates, seems the most trustworthy to date. The

authors note, however, that they surveyed only women between 18 and 33

years of age and did not address physical or psychological stress factors.

A 1990 Macworld article by noted industry critic, Paul Brodeur, proposed

that users maintain the following distances to minimize VLF and ELF


. 28 inches or more from the video screen

. 48 inches or more from the sides and backs of any VDTs.

Although these guidelines seem overly cautious, a fundamental principle is

that magnetic field strength diminishes rapidly with distance. Users could,

for example, select fonts with larger point sizes to permit working farther

from the screen. Remember that magnetic fields penetrate walls.

Over-reaction to ELF and VLF radiation can also compromise ergonomics. In a

campus computer lab, for example, all displays and keyboards were angled

thirty degrees from the front of desktops to reduce the radiation exposure

of students behind the machines. The risks of poor working posture in this

case appear to be greater than the radiation risks.

A final form of radiation, static electric, can cause discomfort by

bombarding the user with ions that attract dust particles, leading to eye

and skin irritations. Anti-static pads, increasing humidity, and grounded

glare screens are effective remedies for these symptoms.

A continuing process

Massive computerization of offices, laboratories, dormitories, and homes

represents a fundamental change in the way many of us work and communicate.

It would be surprising if there were no adverse effects from such profound

changes. It would also be surprising if all policy debates were based on

sound scientific evidence, rather than parochial politics and media

exposes. But, as University of Pennsylvania bioengineering professor

Kenneth Foster has written, "One difficulty is that 'safety,' if considered

to be the absence of increased risk, can never be demonstrated. A hazard

can be shown to exist; absence of hazard cannot."

To monitor research and develop institutional guidelines, the University of

Pennsylvania has created a Task Force on Computing in the Workplace, with

representatives from the Offices of Environmental Health and Safety, Fire

and Occupational Safety, Information Systems and Computing, Radiation

Safety, Purchasing, University Life as well as staff and faculty from the

Wharton School and Schools of Engineering, Medicine and Nursing. Interested

© 2007
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